In order to achieve a high efficiency, a high turbine inlet temperature is used in standard gas turbines. As a result, there arise high NOx emission levels and higher life cycle costs. This can be mitigated with a sequential combustion cycle, wherein the compressor delivers nearly double the pressure ratio of a known one. The main flow passes the first combustion chamber (e.g. using a burner of the general type as disclosed in EP 0 321 809 or as in U.S. Pat. No. 4,932,861, also called EV combustor, where the EV stands for environmental), wherein a part of the fuel is combusted. After expanding at the high-pressure turbine stage, the remaining fuel is added and combusted (e.g. using a burner of the type as disclosed in U.S. Pat. Nos. 5,431,018 or 5,626,017 or in U.S. Patent Application Publication No. 2002/0187448, also called a SEV combustor, where the S stands for sequential). Both combustors contain premixing burners, as low NOx emissions involve high mixing quality of the fuel and the oxidizer.
US 2012/0297777 A1 discloses a known secondary burner. The burner, which is an annular combustion chamber, is bordered by opposite walls. These opposite walls define the flow space for the flow of oxidizing medium. This flow enters as a main flow from the high pressure turbine (e.g., behind the last row of rotating blades of the high pressure turbine which is located downstream of the first combustor). This main flow enters the burner at the inlet side. First this main flow passes flow conditioning elements, which are typically turbine outlet guide vanes which are stationary and bring the flow into the proper orientation. Downstream of these flow conditioning elements vortex generators are located in order to prepare for the subsequent mixing step. Downstream of the vortex generators there is provided an injection device or fuel lance 7 which can include a foot and an axial shaft. At the most downstream portion of the shaft fuel injection takes place; in this case fuel injection takes place via orifices/nozzles which inject the fuel in a direction perpendicular to flow direction (cross flow injection). Downstream of the fuel lance there is the mixing zone, in which the air, bordered by the two walls, mixes with the fuel and then at the outlet side exits into the combustion space where self-ignition takes place.